The present invention relates to a semiconductor device technology, and more particularly to a technology that is applicable to a semiconductor device having a power supply circuit.
A DC-DC converter, which is widely used as a power supply circuit, is formed by series-connecting a high-side switch power MOSFET (Metal Oxide Semiconductor Field Effect Transistor) to a low-side switch power MOSFET. The high-side switch power MOSFET has a switch function for DC-DC converter control. The low-side switch power MOSFET has a switch function for synchronous rectification. These two power MOSFETs alternately turn ON/OFF in synchronism with each other to effect power supply voltage conversion.
The DC-DC converter described above is disclosed, for instance, by Japanese Unexamined Patent Publication No. 2002-217416. The technology disclosed by this patent forms a high-side switch with a horizontal power MOSFET and a low-side switch with a vertical power MOSFET.
Further, the technology disclosed, for instance, by Japanese Unexamined Patent Publication No. 2001-25239 uses a resistor and capacitor to reduce noise that is a problem with a DC-DC converter when it is fabricated as a single chip including a control circuit, driver circuit, and power MOSFET.